ASM-1 VCF "external" audio input?

[Sean Costello]

Andrew Schrock wrote:

> Moog transistor ladder designs are pretty nice.. very smooth response, but
> if you're trying to get that aphex twin feel, get a few CEM 3320's!
> (they're still pretty cheap)

For Aphex Twin sounds, the best bet would be to construct a clone of the
Korg MS-20 filters. You could get a Sallen-Key topology out of a 3320,
but you wouldn't have independent cutoff for the highpass and lowpass
filters, and you certainly wouldn't have the raunchiness of the original
MS-20 filters.  The MS-20 filters can be constructed using the 13600
dual OTA, which is available for 80 cents or so from Mouser.  A nice
schematic can be found at
http://www.mindspring.com/~vco/maxx2/page_015.html, or check Music
Machines at Hyperreal for the original schematic.

Sean Costello